The present invention relates to a driver IC having an inspection function, and an inspection method for the driver IC. The present invention also relates to an inspection method for an output device driven by a driver IC having an inspection function, such as a display device including a liquid crystal, organic EL, or LED, or a printer.
A driver IC includes a number of output pads (banks) at least along the direction of the long side of an IC chip. The driver IC is subjected to various types of inspection in a state formed on a semiconductor wafer or in a completed state after packaging. The inspection is performed by supplying an inspection signal to the driver IC after supplying an inspection command, and monitoring the output from the driver IC.
As an example of this type of inspection, a pad-to-pad leakage test can be given. In the case of a display driver IC including a display RAM, the presence or absence of leakage is determined by writing inspection data into the RAM so that signals at different signal levels are output from adjacent output pads, and measuring the entire current which flows from a power supply in the driver IC when causing the display driver IC to drive a display.
Therefore, programming of write pattern setting, display duty setting (screen partial display), and display ON setting into the RAM is necessary when inspecting the driver IC including a RAM so that such outputs are output from the output pads.
The output pad arrangement of the driver IC is not limited to the arrangement in which the output pads are arranged in one line along the long side of the driver IC as described later in detail. Therefore, since the pad-to-pad leakage test must be manually performed corresponding to the type of driver IC taking the output pad arrangement into consideration, the operation is complicated and a considerable amount of time is required for programming. In this operation, a pattern signal must be supplied from the outside not only to a driver IC including a RAM, but also to a driver IC which does not include a RAM.
The above-described problem is not limited to the pad-to-pad leakage test. For example, when inspecting an output device driven by a driver IC, such as a display device including a liquid crystal panel, organic EL panel, or LED, or a printer, it is necessary to inspect the output device by supplying various pattern signals to the driver IC.
Japanese Patent Application Laid-open No. 6-186279 was found as a conventional technology as a result of search for the pad-to-pad leakage test. However, Japanese Patent Application Laid-open No. 6-186279 does not provide the IC with an inspection function and is irrelevant to the subject matter of the present invention.